Optimal parameter selection for efficient memory integrity verification using merkle hash trees

A secure, tamperproof execution environment is critical for trustworthy network computing. Newly emerging hard-ware, such as those developed as part of the TCPA and Pal-ladium initiatives, enables operating systems to implement such an environment through Merkle hash trees. We exam-ine the selection of optimal parameters, namely blocksize and tree depth, for Merkle hash trees based on the size of the memory region to be protected and the number of memory updates between updates of the hash tree. We analytically derive an expression for the cost of updating the hash tree, show that there is an optimal blocksize for the leaves of a Merkle tree for a given filesize and update interval that min-imizes the cost of update operations, and describe a general method by which the parameters of such a tree can be de-termined optimally. 1